The present invention relates to solar heat collectors and more particularly to a buoyant balloon solar heat collector which floats at a sufficient altitude to avoid normal ground shadows.
A number of references are known to the present applicant which teach various forms of spherical solar heat collectors. These include the following U.S. Pat. Nos.: 3,934,573 issued to Dandini on Jan. 27, 1976; 4,034,735 issued to Waldrip on July 12, 1977; 4,043,315 issued to Cooper on Aug. 23, 1977; 4,056,093 issued to Barger on Nov. 1, 1977; and 4,081,289 issued to Campbell, III, on Mar. 28, 1978. While each of these patents teaches generally the usefulness of a spherical solar heat collector for receiving solar energy from all directions, they each also include various reflectors, or lenses, for energy concentration. The Cooper patent, for example, provides both reflective surfaces for directing solar energy to the spherical collector and numerous lenses on a spherical surface for focusing the reflected energy towards an absorbing device located within the spherical collector. In the Barger and Campbell, III, patents, a fluid-filled sphere acts as a lens to focus energy to a collecting surface below or within the sphere respectively.
Another patent believed to be relevant to the present invention is U.S. Pat. No. 4,002,158 issued to Radebold on Jan. 11, 1977. This patent teaches the construction of a hydrazine generator at an altitude of 10 to 20 kilometers above the earth's surface for the collection of solar energy. Part of this device includes parabolic solar reflectors constructed from inflatable elements which provide buoyancy to the solar energy collecting structure.
Thus it can be seen that there is great interest in providing means for collecting and using the essentially free solar energy. The above references point out the desirability of having a solar heat collector positioned at an altitude above the earth's surface where shadows will not reduce the efficiency of the device, but they also generally show that relatively complicated and expensive support structures are needed to place the devices at the desired elevation. Since the known devices typically use lenses or reflective mirrors, they tend to be relatively heavy and thus require heavy-duty support means. Other simpler devices are filled completely or substantially with a working fluid such as water, which is also extremely heavy, and thus requires heavy supporting structures.